Chiral terpenes in different phases: R-(−)-camphorquinone studied by IR–Raman–VCD spectroscopies and theoretical calculations
Juan Ramón Avilés Moreno, Francisco Partal Ureña, Juan Jesús López González
R-(−)-camphorquinone is a bicyclical terpenoid with many usages and application in different fields. Different experimental and theoretical works reveal that there is only one stable conformer of this chiral chemical species in agreement to the sterical restriction that the bicycle introduces. In the current work, from a complete assignment of the vibrational IR and Raman spectra, we are able to explain the VCD spectrum of the title compound. The recorded spectra of R-(−)-camphorquinone in different phases have been analyzed and compared: the first one in CCl4 solution, the second one using Nujol and Fluorolube suspensions and the third one using thin films. Finally, to study the coupling between the two C=O stretching normal modes, a NBO analysis is performed. The present work reveals that IR, Raman and VCD, combined with quantum chemical calculations, are helpful complementary techniques to characterize chiral systems, as terpenes, in different phases.
Vibrational circular dichroism, R-(−)-camphorquinone, Quantum chemical calculations,